A novel approach to evaluate blood hemodynamics in the retina is nearly completed. This is a highly-modified fluorescein angiography system utilizing automated computerized microdensitometric analysis of the films for an accurate and reproducible calculation of retinal circulation time. Built into the procedure is an evaluation of vitreous fluorescein leakage utilizing a modified slit lamp with a fiberoptic probe and photomultiplier electronics. After the standardization of this clinical investigative retinal evaluatory system, day to day and week to week reproducibility will be established in normal controls, the offspring of two diabetic patients and in established diabetics. When the degree of clinical physiological reproducibility has been established, norms will be established in a broad group of normal individuals (both males and females) ranging in age from 15 to 70 years. Parallel to this will be studies focused on the offspring of two diabetic parents, particularly those who show intermittent carbohydrate intolerance. In addition, this system will be utilized for the pospective charactrization of a population of juvenile-onset diabetics (one group with retinopathy and one group without retinopathy) and buttressed with multiple metabolic studies including the usual clinical glycemic entities, glycosylated hemoglobin, and plasma lipids. The earliest possible stages of diabetic retinal microangiopathy and/or the degree of retinopathy will be evaluated and correlated with these metabolic determinants.